15 bursts of radio emission detected from dwarf galaxy 3 billion light years away

Last Saturday, a telescope in a remote area of West Virginia picked up those 15 bright radio burst signals from a distant corner of the universe, and yesterday, a group of astronomers and astrophysicists shared preliminary results on their observations.

They detected 15 bursts above our detection threshold of 10 sigma in the first two 30-minute scans. They include the detection signal-to-noise ratio (SNR) of each burst, along with a very rough estimate of pulse energy density assuming a 12 Jy system equivalent flux density, 300 us pulse width, and uniform 3800 MHz bandwidth.

Breakthrough Listen is a global astronomical initiative launched in 2015 by Internet investor and philanthropist Yuri Milner and cosmologist Stephen Hawking. As part of their program to observe nearby stars and galaxies for signatures of extraterrestrial technology, the Listen science team at UC Berkeley added FRB 121102 to their list of targets. In the early hours of Saturday, August 26, UC Berkeley Postdoctoral Researcher Dr. Vishal Gajjar observed the location of FRB 121102 using the Breakthrough Listen backend instrument at the Green Bank Telescope in West Virginia. The instrument accumulated 400 TB of data on the object over a five hour observation, observing the entire 4 to 8 GHz frequency band. This large dataset was searched for signatures of short pulses from the source over a broad range of frequencies, with a characteristic dispersion, or delay as a function of frequency, caused by the presence of gas in space between us and the source. The distinctive shape that the dispersion imposes on the initial pulse is an indicator of the amount of material between us and the source, and hence an indicator of the distance to the host galaxy.

Analysis by Dr. Gajjar and the Listen team revealed 15 new pulses from FRB 121102. As well as confirming that the source is in a newly active state, the high resolution of the data obtained by the Listen instrument will allow measurement of the properties of these mysterious bursts at a higher precision than ever possible before.

The observations also show for the first time that FRBs emit at higher frequencies (with the brightest emission occurring at around 7 GHz) than previously observed. The extraordinary capabilities of the Listen backend, which is able to record several gigahertz of bandwidth at a time, split into billions of individual channels, enable a new view of the frequency spectrum of FRBs, and should shed additional light on the processes giving rise to FRB emission.

When the recently-detected pulses left their host galaxy our entire Solar System was just 2 billion years old. Life on Earth consisted of only single-celled organisms, and it would be another billion years before even the simplest multi-cellular life began to evolve. Whether or not FRBs eventually turn out to be signatures of extraterrestrial technology, Breakthrough Listen is helping to push the frontiers of a new and rapidly growing area of our understanding of the Universe around us.

Breakthrough Listen is a scientific program in search for evidence of technological life in the Universe. It aims to survey one million nearby stars, the entire galactic plane and 100 nearby galaxies at a wide range of radio and optical bands.

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